Cardiac diagnostics using wall motion and perfusion cardiac mri imaging and systems for cardiac diagnostics

ABSTRACT

Cardiac information of a patient is displayed by obtaining a plurality of MRI cine loops of the heart of the patient at a plurality of heart rates, the plurality of cine loops including both wall motion cine loops and at least one perfusion cine loops and simultaneously displaying both the wall motion cine loops and the at least one perfusion cine loop.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/628,915 filed Jul. 29, 2003, which claims the benefit of priority ofU.S. Provisional Patent Application Ser. No. 60/399,275, filed Jul. 29,2002, and U.S. Provisional Patent Application Ser. No. 60/421,708, filedOct. 28, 2002, the contents of which are hereby incorporated byreference as if recited in full herein.

FIELD OF THE INVENTION

The present invention is related to cardiac diagnostics and moreparticularly to stress test cardiac diagnostics using magnetic resonanceimaging (MRI) methods.

BACKGROUND OF THE INVENTION

The heart is a muscle that continuously pumps blood, transporting lifesustaining oxygen and nutrients to the major organs and tissues of thebody. As such, the heart needs a large supply of oxygen and nutrients.The heart receives its blood from three major coronary arteries. If anyone of these arteries becomes narrowed or blocked, blood flow and oxygento the heart is restricted, the performance of your blood pump isimpaired, and permanent damage to the heart can occur. An impaired ordamaged heart can significantly impact quality of life and even resultin death.

Coronary artery disease (CAD) is the primary cause of narrowing andblockage of the arteries to or in the heart. It is the leading cause ofdeath in the United States. Although the rate of death due to CAD hasdeclined steadily over the last few decades, the overall incidence ofCAD and the impact it will have on the population and the cost of healthcare is expected to grow dramatically over the next 20-30 years due tothe aging population. CAD already costs the U.S. an estimated $100billion annually in medical care and lost productivity. Therefore, thetests for CAD that can improve the accuracy of cardiac evaluations,particularly in early stage coronary heart disease/CAD, may bebeneficial. Tests that may allow physicians to make explicit diagnosesand treatment plans, that may reduce unnecessary tests, surgeries andhospital stays, may reduce anxiety, discomfort and risk to the patientand/or may allow for the assessment of therapeutic efficacy may beparticularly beneficial.

The ability to mitigate and circumvent the effects of CAD has improvedover the years as a result of the prior development of increasinglysophisticated cardiac tests and procedures. The “gold standard” ofcardiac tests is generally recognized as cardiac catheterization andangiography. This test is most commonly used in determining the locationand the severity of the effects of CAD. However, a cardiaccatheterization procedure is an expensive procedure that typicallyrequires hospitalization because it is invasive and has potential forcomplications. As a result, cardiac catheterization procedures aregenerally only used when a patient has undergone other non-invasivetests such as cardiac stress tests with significant abnormal results.More than one million cardiac catheterization procedures are performedeach year at a cost estimated to be between about $3-$5 billion.

Cardiac stress tests may be particularly important in evaluating theheart and its coronary arteries because often the presence of CAD andits effects are missed when tests are performed on a patient at rest. Itis only when the heart is stressed by either exercise on a treadmill orexercise bike, or where the maximal exercise is simulated by theintroduction of special chemicals or drugs (drug-induced stress) to theheart of patients who for various reasons are unable to perform actualphysical exercise, that the symptoms of CAD can be reliably detectedover much of the population. Currently, the most commonly used stresstests include the exercise (treadmill) stress test, the stressechocardiogram (ultrasound), and the nuclear perfusion stress test.

These three tests have varying levels of complexity, accuracy,availability, and cost. The ECG exercise stress test is the most widelyavailable and used stress test and the least costly to administer. Itrelies on detection of changes in ST segments on a 12-leadechocardiogram; it is variable in its accuracy, producing a significantnumber of false positive and negative results. Consequently, patientsoften undergo supplemental imaging during their stress test withechocardiography or radionuclide scintigraphy. The sophistication ofboth echocardiography and radionuclide scintigraphy stress teststypically require that they be administered and evaluated by aspecialist. Typically, a trained ultrasound technician or a cardiologistadministers a stress echocardiogram, and a technician certified in thehandling of radioisotopes along with a cardiologist or radiologistadministers a nuclear perfusion stress test. Results in both testingprotocols generally need to be evaluated by a cardiologist in order tomake an accurate diagnosis. The test selected for administration istypically determined by the cardiologist based on the findings of thephysical and medical history of the patient and the cardiologist'sclinical judgment. Each test has a degree of inaccuracy. Theechocardiography has an almost 10-15% failure rate where a diagnosiscannot be made. Obstacles that may prevent the capture of good imagesfor diagnosis may cause this failure rate. Scar tissue from chestsurgeries, excessive patient body fat and lung disorders that captureexcessive oxygen in the lungs are examples of such obstacles. Stressechocardiography tests, for varying reasons, also produce a significantnumber of false negative results. The nuclear perfusion stress tests arehighly sensitive and are prone to produce an equally significant numberof false positive results.

With over 1.3 million stress echocardiography tests performed each yearwith a 10-15% failure rate, there are potentially over $100 millionunnecessary or clinically unreliable stress echocardiography tests doneeach year. This stress echo failure rate results in an increase in thenumber of nuclear perfusion stress tests, which are known to have a highincidence of false positive results. A false positive cardiac stresstest may increase the number of expensive, unnecessary cardiaccatheterization procedures and their associated required hospital stayand added anxiety, discomfort and medical risk for the patient. Thesignificant number of false negatives from stress echocardiography testsmay increase the risk of heart attacks and sudden death from undetectedadvanced CAD and/or successful earlier intervention in early stages ofCAD.

Accordingly, a need exists for reduced cost, increased accuracy and/orincreased availability stress testing for cardiac diagnostics.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide methods, system and/orcomputer program products for displaying cardiac information of apatient. A plurality of MRI cine loops of the heart of the patient areobtained at a plurality of heart rates and levels of pharmacologicand/or exercise induced stress. The plurality of cine loops includingwall motion cine loops of frames of wall motion images and perfusionimages of at lease one cardiac location. Both the wall motion cine loopsand the perfusion cine loop are simultaneously displayed.

In certain embodiments, the perfusion image is at least one cine loop ofperfusion images of at least one location of the heart. In furtherembodiments, the perfusion image is a myocardial delayed enhancement(MDE) perfusion image of a location of the heart.

In particular embodiments of the present invention, the plurality of MRIcine loops are adjusted so as to provide compensated cine loops having asame number of frames in each of the MRI cine loops. Furthermore, theplurality of MRI cine loops may be acquired while a stress test isadministered to the patient. The displayed MRI cine loops may also beevaluated to determine a presence or absence of myocardial ischemia orviability based on the displayed cine loops.

In further embodiments of the present invention, for a single dosage ofa stress inducing agent or level of exercise, a plurality of cine loopsfor differing locations associated with the heart of the patient aresimultaneously displayed. A plurality of cine loops for a singlelocation associated with the heart of the patient for differing dosagesof a stress inducing drug may also be simultaneously displayed.

In still other embodiments of the present invention, the plurality ofMRI cine loops are adjusted by adding frames to and/or removing framesfrom at least one of the plurality of MRI cine loops. Frames may beadded to and/or removed from respective ones of the MRI cine loops suchthat all of the displayed MRI cine loops have a same number of frames.Furthermore, the additional frames may be provided by repeating framesof an MRI cine loop. The frames that are added or removed may be evenlydistributed throughout an MRI cine loop.

In additional embodiments of the present invention, the wall motion MRIcine loops are compensated such that corresponding frames in each of theplurality of wall motion MRI cine loops correspond to a common portionwithin a cardiac cycle of the patient. Thus, frames in different cineloop may correspond to a different duration of time, time, however, eachframe may correspond to the same percentage of time of the cardiaccycle.

Furthermore, the plurality of MRI cine loops may also be adjusted byadjusting a duration of display of frames of a least one of theplurality of MRI cine loops such that each of the MRI cine loops has acommon total duration. In additional embodiments of the presentinvention, cardiac information of a patient is displayed by obtaining aplurality of MRI cine loops of the heart of the patient at a pluralityof heart rates, the plurality of cine loops including cine loopsincluding frames of wall motion images. At least one perfusion image ofat least one cardiac location is also obtained. Both the wall motioncine loops and the at least one perfusion image are simultaneouslydisplayed.

In certain embodiments of the present invention, the perfusion image isa plurality of perfusion images that provide a cine loop of perfusionimages. In such a case, simultaneously displaying both wall motion cineloops and the at least one perfusion image is provided by simultaneouslydisplaying both wall motion cine loops and the at least one cine loop ofperfusion images.

In other embodiments of the present invention, the perfusion image is amyocardial delayed enhancement perfusion image.

In still further embodiments of the present invention, a user interfacefor MRI imaging evaluation is provided. The user interface may bedisplayed on a display device and includes at least one regionconfigured to display a plurality of cine loops of MRI images of cardiacwall motion and at least one region configured to display at least oneMRI image of cardiac perfusion. The region configured to display atleast one MRI image of cardiac perfusion may be configured to display atleast one cine loop of MRI images of cardiac perfusion. Furthermore, theplurality of cine loops of MRI images of cardiac wall motion may besynchronized to one another and the at least one cine loop of MRI imagesof cardiac perfusion. Also, at least one of the plurality of cine loopsof MRI images of cardiac wall motion may be registered to the cine loopof MRI images of cardiac perfusion.

As will be appreciated by those of skill in the art in light of thepresent disclosure, embodiments of the present invention may be providedas methods, system and/or computer program products.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an MRI system according to embodiments ofthe present invention.

FIG. 2 is a block diagram of a data processing system according toembodiments of the present invention;

FIG. 3 is a more detailed block diagram of a MRI cine loop displaysystem according to embodiments of the present invention;

FIG. 4 is a flowchart illustrating operations according to embodimentsof the present invention.

FIG. 5 is a screen capture of an exemplary cine-loop display.

FIG. 6 is a flowchart illustrating operations according to furtherembodiments of the present invention.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The present invention now will be described more fully hereinafter withreference to the accompanying drawings, in which illustrativeembodiments of the invention are shown. This invention may, however,should not be construed as limited to the embodiments set forth herein;rather, these embodiments are provided so that this disclosure will bethorough and complete, and will fully convey the scope of the inventionto those skilled in the art.

As will be appreciated by one of skill in the art, the present inventionmay be embodied as methods, systems, or computer program products.Accordingly, the present invention may take the form of an entirelyhardware embodiment, an entirely software embodiment or an embodimentcombining software and hardware aspects all generally referred to hereinas a “circuit” or “module.” Furthermore, the present invention may takethe form of a computer program product on a computer-usable storagemedium having computer-usable program code embodied in the medium. Anysuitable computer readable medium may be utilized including hard disks,CD-ROMs, optical storage devices, a transmission media such as thosesupporting the Internet or an intranet, or magnetic storage devices.

Computer program code for carrying out operations of the presentinvention may be written in an object oriented programming language suchas Java®, Smalltalk or C++. However, the computer program code forcarrying out operations of the present invention may also be written inconventional procedural programming languages, such as the “C”programming language. Particular cine display systems may utilizeinteractive data language (IDL) programming to provide cine displayssuitable for use in embodiments of the present invention. The programcode may execute entirely on a user's computer, partly on the user'scomputer, as a stand-alone software package, partly on the user'scomputer and partly on a remote computer or entirely on the remotecomputer. In the latter scenario, the remote computer may be connectedto the user's computer through a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).Furthermore, the user's computer, the remote computer, or both, may beintegrated into other systems, such as an MRI system.

The present invention is described below with reference to flowchartillustrations and/or block diagrams of methods, apparatus (systems) andcomputer program products according to embodiments of the invention. Itwill be understood that each block of the flowchart illustrations and/orblock diagrams, and combinations of blocks in the flowchartillustrations and/or block diagrams, can be implemented by computerprogram instructions. These computer program instructions may beprovided to a processor of a general purpose computer, special purposecomputer, or other programmable data processing apparatus to produce amachine, such that the instructions, which execute via the processor ofthe computer or other programmable data processing apparatus, createmeans for implementing the functions/acts specified in the flowchartand/or block diagram block or blocks.

These computer program instructions may also be stored in acomputer-readable memory that can direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer-readablememory produce an article of manufacture including instruction meanswhich implement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer orother programmable data processing apparatus to cause a series ofoperational steps to be performed on the computer or other programmableapparatus to produce a computer implemented process such that theinstructions which execute on the computer or other programmableapparatus provide steps for implementing the functions/acts specified inthe flowchart and/or block diagram block or blocks.

Embodiments of the present invention provide for the cardiac diagnosticsutilizing both wall motion MRI cine loops of the heartbeat of a patientand perfusion images. The perfusion images may be cine loops of MRIperfusion images and/or individual images, such as may be provide bymyocardial delayed enhancement. The wall motion MRI cine loops may betemporally synchronized MRI cine loops adjusted to compensate fordifferent heart rates, such as stress induced heart rates, and,accordingly, different cardiac cycle patterns and/or durations. Cardiacdiagnostics are performed by evaluating the temporally synchronized MRIcine loops and one or both of perfusion images or MRI cine loops of apatient being subjected to stress testing. Such evaluation may result ina screening determination as to the likelihood a patient has CAD.

An exemplary system 10 according to embodiments of the present inventionis illustrated in FIG. 1. As seen in FIG. 1, a cine display/MRI system10 includes an MRI acquisition system 11 that may include an MRI controlsystem circuit 12, an MRI pulse excitation system circuit 14 and an MRIsignal measurement system circuit 16. The MRI control system circuit 12controls operations of the MRI acquisition system 11 to obtain andprovide MRI images during a cardiac cycle of a patient. The MRI controlsystem circuit 12 may also assemble and transmit the acquired images toa workstation 20 or other such data processing system for furtheranalysis and/or display. The workstation 20 may be in an MRI suite ormay be remote from the MRI suite. The MRI pulse excitation systemcircuit 14 and the MRI signal measurement system circuit 16 arecontrolled to acquire MRI signals that may provide MRI images of theheart of a patient.

The MRI images may be acquired, for example, utilizing a fast gradientecho segmented k-space sequence. The k-space segmentation may beadjusted to provide adequate temporal resolution (13-65 msec) foridentification of end of systole, with the end-systolic frame typicallybeing the frame with the smallest left ventricle (LV) cavity dimensions.View sharing may be utilized to provide an intermediate frame betweenacquired frames. The table below provides an example of the adjustmentof k-space segmentation for differing heart rates.

Temporal Breathhold Heart Rate Views Resolution Duration (beats/min) perSegment (msec) (sec) <55 10 65 10 55-65 8 52 13-11 65-95 6 39 15-10 95-125 4 26 15-12 125-170 2 13 23-17Alternatively, images may be acquired with other MRI techniqueshighlighting thickening or relaxation of the LV myocardium.

The MRI images of wall motion and perfusion of the frames of the cineloops may include corresponding images of different locations of theheart and at different times during the cardiac cycle of the patient (i.e. cine loops may be registered to other cine loops). For example, theimages may include slices such as the basal short axis, the long axis,the mid short axis, the apical short axis, four chamber and two chamberslices. In particular embodiments, the desired image locations may beselected so as to provide images of LV wall motion. Furthermore, theimages may be from different times during a stress test of the patient,for example, at a baseline or resting heart rate and/or at differentheart rates and/or different dosages of stress inducing agents, such asdobutamine and atropine.

Myocardial perfusion images will be acquired at rest and during stress(pharmacologic or exercise) upon the administration of paramagneticcontrast agents (such as those containing gadolinium) or susceptibilityagents (such as those containing iron oxide or dysprosium), or withoutthe administration of contrast incorporating techniques such asblood-oxygen level dependent (BOLD) cardiac imaging using a T2 preparedpulse sequence or a 3D T2 weighted sequence. The acquired cardiac wallperfusion images may be images of a single location within the cardiacregion taken over multiple successive heartbeats. The perfusion imagesmay also be generated and displayed to provide a cine loop having thesame number of frames as the corresponding temporally compensated MRIcine loops of wall motion.

Conventional MRI systems, such as those provided by General ElectricMedical Systems, Siemens, Philips, Varian, Bruker, Marconi and Toshibamay be utilized to provide the desired MRI image frames collected duringheartbeats of a patient undergoing stress testing that may be temporallycompensated and displayed and/or analyzed for biophysical orbiophysiological abnormalities for cardiac diagnostics according toembodiments of the present invention as described herein.

While an exemplary cine display/MRI system is illustrated in FIG. 1 anddescribed herein with a particular division of functions and/oroperations, as will be appreciated by those of skill in the art, otherdivisions of functions and/or operations may be utilized while stillbenefiting from the teachings of the present invention. For example, theMRI control system circuit 12 could be combined with either the MRIpulse excitation system circuit 14 or the MRI signal measurement systemcircuit 16. Thus, the present invention should not be construed aslimited to a particular architecture or division of MRIfunctions/operations but is intended to cover any architecture ordivision of functions/operations capable of carrying out the operationsdescribed herein.

FIG. 2 illustrates an exemplary embodiment of a data processing system230 suitable for providing a workstation 20 and/or MRI control systemcircuit 12 in accordance with embodiments of the present invention. Thedata processing system 230 typically includes input device(s) 232 suchas a keyboard or keypad, a display 234, and a memory 236 thatcommunicate with a processor 238. The data processing system 230 mayfurther include a speaker 244, and an I/O data port(s) 246 that alsocommunicate with the processor 238. The I/O data ports 246 can be usedto transfer information between the data processing system 230 andanother computer system or a network. These components may beconventional components such as those used in many conventional dataprocessing systems that may be configured to operate as describedherein.

FIG. 3 is a block diagram of embodiments of data processing systems thatillustrates systems, methods, and computer program products inaccordance with embodiments of the present invention. The processor 238communicates with the memory 236 via an address/data bus 348. Theprocessor 238 can be any commercially available or custommicroprocessor. The memory 236 is representative of the overallhierarchy of memory devices containing the software and data used toimplement the functionality of the data processing system 230. Thememory 236 can include, but is not limited to, the following types ofdevices: cache, ROM, PROM, EPROM, EEPROM, flash memory, SRAM, and DRAM.

As shown in FIG. 3, the memory 236 may include several categories ofsoftware and/or data used in the data processing system 230: theoperating system 352; the application programs 354; the input/output(I/O) device drivers 358; and the data 356. As will be appreciated bythose of skill in the art, the operating system 352 may be any operatingsystem suitable for use with a data processing system, such as OS/2, AIXor System390 from International Business Machines Corporation, Armonk,N.Y., Windows95, Windows98, Windows2000, WindowsNT or WindowsXP fromMicrosoft Corporation, Redmond, Wash. Unix or Linux. The operatingsystems may be configured to support an TCP/IP-based or other suchnetwork communication protocol connection. The I/O device drivers 358typically include software routines accessed through the operatingsystem 352 by the application programs 354 to communicate with devicessuch as the I/O data port(s) 246 and certain memory 236 components. Theapplication programs 354 are illustrative of the programs that implementthe various features of the data processing system 230 and preferablyinclude at least one application that supports operations according toembodiments of the present invention. Finally, the data 356 representsthe static and dynamic data used by the application programs 354, theoperating system 352, the I/O device drivers 358, and other softwareprograms that may reside in the memory 236.

As is further seen in FIG. 3, the application programs 354 may include acine-loop processing application 360. The cine-loop processingapplication 360 may carry out the operations described herein fortemporally synchronizing cine loops of MRI images, displaying temporallysynchronized cine loops of MRI images of cardiac wall motion and/orcardiac wall perfusion images and/or evaluation of temporallysynchronized cine loops of MRI images. The data portion 356 of memory236, as shown in the embodiments of FIG. 3, may include MRI image data362 that includes cine loops of MRI images of wall motion and perfusion.

While the present invention is illustrated, for example, with referenceto the cine-loop processing application 360 being an application programin FIG. 3, as will be appreciated by those of skill in the art, otherconfigurations may also be utilized while still benefiting from theteachings of the present invention. For example, the cine-loopprocessing application 360 may also be incorporated into the operatingsystem 352, the I/O device drivers 358 or other such logical division ofthe data processing system 230. Thus, the present invention should notbe construed as limited to the configuration of FIG. 3 but is intendedto encompass any configuration capable of carrying out the operationsdescribed herein.

FIG. 4 illustrates operations according to certain embodiments of thepresent invention. As illustrated in FIG. 4, a stress test isadministered to a patient (block 400) and MRI images of the heart of thepatient indicating wall motion and perfusion are acquired during thestress test (block 402). The stress test may be any type of stress testthat may be administered while MRI images are acquired. In particularembodiments the MRI stress test is a biochemically induced stress testusing an agent such as dobutamine or the like. The administration ofcardiac stress tests are known to those of skill in the art and,therefore, are not described further herein.

The acquired perfusion images may be “first-pass” perfusion images thatare acquired shortly after a contrast agent is administered. In such acase, the perfusion images may be a cine loop of images such that theperfusion of the contrast agent may be tracked or monitored by the cineloop images. The perfusion cine loop images may be multiple perfusioncine loop images for different locations of the heart. These cine loopsmay be registered to the wall motion cine loop images such thatperfusion cine loops correspond to substantially the same locations asthe wall motion cine loops. For example, the perfusion cine loops may bethree cine loops corresponding to the three short axis wall motion cineloops. Thus, the perfusion images may be acquired at the same planesthrough the heart as the short axis wall motion images.

Alternatively, or in addition to the generation of a cine loop ofperfusion images, myocardial delayed enhancement (MDE) may also beprovided. In MDE, 20 minutes after a contrast agent, such as gadoliniumDPTA, is administered, some of it has leaked into necrotic (dead) tissueand will appear bright (hence, delayed enhancement). These images may beacquired not as cine loops, but as single images, registered (at thesame slice locations) with the corresponding perfusion and/or wallmotion images. MDE is another form of perfusion, that is, it isperfusion of dead tissue, while first-pass perfusion is perfusion ofliving tissue. Thus, the perfusion images may include single images,such as MDE images, and/or cine loops of images. One or both may bedisplayed with the wall motion images.

The MRI images of wall motion, which may provide cine loops of heartbeats at differing locations of the heart and/or different dose levelsof a stress inducing agent, are temporally synchronized and the numberof perfusion images is established such that each cine loop has the samenumber of MRI images or frames so that each cine loop maybe displayedfor the same duration (block 404). Thus, for example, the perfusion cineloops may be synchronized to the wall motion cine loops by having themplay cyclically at the same rate as the wall motion images. Thesynchronization of perfusion cine loops may also be accomplished byadding frames, dropping frames or adjusting the duration of display offrames as described herein. The cine loops of wall motion may also besynchronized to the cardiac cycle such that each cine loop begins at thesame portion of the cardiac cycle.

The compensated cine loops of wall motion and the perfusion imagesand/or cine loops of perfusion images may be provided, for example, to aworkstation for display, and may both be evaluated to assess a state ofcardiac physiology of the patient (block 406). Such an assessment may bemade, for example, by displaying the wall motion and perfusion cineloops for a given location for several or all doses and/or displayingthe cine loops for several or all locations for a given dose. Bydisplaying the images as they are acquired near real time evaluation maybe performed. Additionally or alternatively, an MDE image or images mayalso be displayed with the wall motion cine loops. The displayed cineloops and/or image(s) may be evaluated by a physician to assess cardiacphysiology. Such an assessment may include, for example, a determinationof the presence or absence of CAD, a change in the severity of CAD, theefficacy of a cardiac treatment regime or the like. For example, theperfusion images may be compared to the wall motion images to determineif an area of reduced perfusion corresponds to an area with defectivewall motion, thus, providing further confirmation that an occlusion mayexist.

These operations may be repeated until the MRI images for the desiredlocations (block 408) and for the desired stress test levels (block 410)are obtained and compensated as described herein. Thus, if additionalviews are to be acquired (block 408) operations continue with obtainingadditional MRI images (block 402). If additional stress levels are to beevaluated (block 410), operations continue with the administration ofadditional stress tests (block 400).

The temporal synchronization of the cine loops has been found to allowphysicians to evaluate cardiac physiology more effectively withoutintroducing significant artifacts and/or distortions through thetemporal synchronization process that would obscure information orprovide false information that would lead to invalid evaluations.Furthermore, the temporal synchronization of the cine loops has beenfound to increase the effectiveness of the evaluation of MRI cine loopsas it allows the physician to simultaneously visually compare heartmotion at different heart rates where the display heart motion issynchronized to the same portion within the cardiac cycle. Thus, eachdisplayed image is at approximately the same percent of time within aheart beat. Accordingly, differences in wall motion at different heartrates may be directly compared to detect any abnormality. As discussedabove, it has been found that the temporal synchronization processdescribed herein allows for such a display without introducinginaccuracies, artifacts or other such distortions that would hinder theevaluation process. Furthermore, the evaluation process may be performedin a sufficiently real-time manner so as to allow a physician to utilizethe MRI cine loops to monitor a stress test while the stress test isbeing performed. Such monitoring may be useful both in administering thestress test and in evaluation of a patient's condition based on theresults of the stress test. By providing the cine loop information in aform that allows for simultaneous direct comparison of data fordiffering heart rates a physician may rapidly assess the cardiacphysiology of a patient so as to adjust parameters of the test and/oravoid injury to the patient.

In several conditions, for example, the presence of resting wall motionabnormalities throughout the course of the stress test, or the presenceof concentric left ventricular hypertrophy, assessment of wall motion isnot adequate for identifying ischemia. For this reason, the combinedassessment of myocardial perfusion and/or delayed enhancement and cinewall motion may enhance a reader's ability to identify areas ofmyocardial necrosis or ischemia not evident with assessments of wallmotion alone.

In still further embodiments of the present invention, the evaluation ofthe cine loops may be performed automatically or partially automaticallyutilizing image processing techniques. Such an automatic evaluation maybe facilitated by the temporal synchronization of the cine loops as datasets having a common size would be provided and corresponding frameswithin the data sets would correspond to a common portion within acardiac cycle. For example, the cine loops or a portion of the imageswithin the cine loops may be compared to each other or a reference so asto highlight deviations from a baseline cine loop. Thus, for example, abaseline wall motion cine loop may be compared to differing dose cineloops and the differences displayed and/or compared to thresholds so asto provide an indication and/or assessment of cardiac physiology. Thesedifferences could also be compared with a perfusion cine loop or loopsof the same region and areas of low perfusion compared to areas ofabnormal wall motion. Such a comparison of the cine loops may be madepossible and/or simplified because the location within each cine loopcorresponds to approximately the same time within the cardiac cycle suchthat similarly situated frames within differing cine loops may bedirectly compared to each other.

An automatic comparison may, for example, also include registration ofthe differing cine loops to the baseline loops. Such a registration maybe provided utilizing conventional pattern recognition and/or alignmenttechniques such that corresponding pixels of the cine loops or portionsof the cine loops are each associated with approximately the samephysical location within the patient. In particular embodiments, thecomparisons may be 3 (x,y, t), 4 (x,y,z,t) and/or 5 (x,y,z,t,dose)dimensional.

The cine loops may be compensated by repeating images, increasing ordecreasing the time an image is displayed and/or by removing images fromthe cine loops. The cine loops may be temporally synchronized byproviding the same number of images or frames in each loop. Thus, eachdisplayed heartbeat of the patient may be displayed for the same periodof time irrespective of the heart rate at which the cine loop wasacquired. Loops which have more frames may have frames removed and loopswith fewer frames may have frames added. Frames may be added byrepeating frames in the loop. Frames may be added in a virtual manner byincreasing the duration that a frame is displayed. Such a virtualaddition of frame may need less storage requirement than the physicalrepetition of frames in a loop. The frames added or removed may bedistributed throughout the loop and are preferably distributedsubstantially evenly throughout the loop. Furthermore, the cine loopsmay be synchronized to the patients cardiac cycle such that each cineloop begins at approximately the same part in the cardiac cycle.Techniques for synchronizing MRI cine loops to the cardiac cycle of apatient are known to those of skill in the art and, therefore, need notbe described further herein.

In particular embodiments of the present invention the display of cineloops is provided in real time. In other embodiments, the display ofcine loops is provided in near real time. Such real time or near realtime display of cine loops of a patient undergoing stress testing may beutilized to provide safe stress testing by allowing for rapid analysisand monitoring of the stress test such that patient injury may beavoided. In still other embodiments, the display of cine loops isprovided from stored information and may be performed “off-line.” Suchoff-line analysis may be suitable for detailed or more time consuminganalysis of the cine loops. Furthermore, the acquisition of data,construction of images and/or the transfer of images of a cine loop maybe overlapped with each other so as to reduce apparent latency betweenthe acquisition and the display of images.

FIG. 5 is a screen capture of a cine loop display 500 according toembodiments of the present invention. As seen in FIG. 5, a plurality ofcine loops 502 are simultaneously displayed. The cine loops have beentime synchronized as described above and include displays of wall motionand perfusion information. As is seen in FIG. 5, wall motion cine loops,first-pass perfusion cine loops and MDE images may all be displayedsimultaneously. In FIG. 5, a baseline wall motion cine loop 502, a firstdose wall motion cine loop 504, a peak dose wall motion cine loop 506, arecovery wall motion cine loop 508, a first-pass perfusion cine loop 510and a delayed enhancement image 512 are simultaneously displayed asdescribed herein.

FIG. 6 illustrates operations according to further embodiments of thepresent invention. As seen in FIG. 6, user input may be obtained to cropa cine loop base image and/or to adjust contrast, brightness, gamma orother display levels of the base cine loop image (block 600). Thecropping and/or level adjustment may then be propagated automatically tothe remaining images in the base cine loop and to the other cine loopsthat are displayed or are stored (block 604). Thus, a physician mayrapidly adjust the display of the cine loop images without the need toadjust each image and/or loop individually. Optionally, the croppingand/or level information may be stored and associated with the cineloops. The cine loops may also be stored, for example, on a hard driveor other storage media, and recalled at a later time for display and/oranalysis. The stored cine loops could then be displayed with thecropping and/or level information automatically applied.

While embodiments of the present invention have been described primarilywith reference to near real time evaluation of the MRI images, as willbe appreciated by those of skill in the art in light of the presentdisclosure, evaluation of the MRI images could also occur “off line” orafter a substantial delay. For example, prior MRI images could bedisplayed and compared with current MRI images to determine ifimprovement, possibly resulting from a course of treatment, has occurredin wall motion and/or perfusion. Thus, the present invention should notbe construed as limited to the evaluation of MRI cine loop imagesimmediately after acquisition.

The foregoing is illustrative of the present invention and is not to beconstrued as limiting thereof. Although a few exemplary embodiments ofthis invention have been described, those skilled in the art willreadily appreciate that many modifications are possible in the exemplaryembodiments without materially departing from the novel teachings andadvantages of this invention. Accordingly, all such modifications areintended to be included within the scope of this invention as defined inthe claims.

1. A system with a user interface for cardiac stress test evaluationusing MRI image data, comprising: a display having a user interface, thedisplay configured to present: at least one region configured to displaya plurality of temporally synchronized cine loops of MRI images ofcardiac wall motion at different heart beat rates of a patientundergoing cardiac stress test evaluation; and at least one regionconfigured to display at least one MRI image of cardiac perfusion of thepatient thereby providing visual data for cardiac stress testevaluation.
 2. The system of claim 1, wherein the at least one regionconfigured to display at least one MRI image of cardiac perfusiondisplays at least one cine loop of MRI images of cardiac perfusion, andwherein the at least one cine loop of MRI images of cardiac perfusion issynchronized to cyclically display at the same rate as the wall motioncine loops.
 3. The system of claim 2, wherein the plurality of cineloops of MRI images of cardiac wall motion are synchronized to oneanother and the at least one cine loop of MRI images of cardiacperfusion.
 4. The system of claim 2, wherein at least one of theplurality of cine loops of MRI images of cardiac wall motion isregistered to the at least one cine loop of MRI images of cardiacperfusion.
 5. The system of claim 1, wherein the display with the userinterface is configured to display the plurality of cine loops of MRIimages of cardiac wall motion and the at least one MRI image of cardiacperfusion in real-time or near real-time.
 6. The system of claim 1,wherein the user input is configured to accept user input to rapidlyadjust at least one of contrast, brightness, gamma or another displaylevel of a baseline cine loop image, which is then automaticallypropagated to the other cine loops without adjusting each one separatelyto thereby provide a clinician with patent information for saferadministration of the cardiac stress test.
 7. A clinician workstationfor evaluating cardiac stress tests, comprising: at least one display;and a user interface in communication with the display, wherein the atleast one display is configured to show a plurality of temporallysynchronized cine loops of MRI images of cardiac wall motion atdifferent heart beat rates of a patient undergoing stress testevaluation concurrently with at least one MRI image of cardiac perfusionof the patient thereby providing visual data for cardiac stress testevaluation.
 8. The workstation of claim 7, wherein the at least onedisplay is a single display, wherein the at least one MRI image ofcardiac perfusion comprises at least one cine loop of MRI images ofcardiac perfusion, and wherein the at least one cine loop of MRI imagesof cardiac perfusion is synchronized to cyclically display at the samerate as the wall motion cine loops.
 9. The workstation of claim 8,wherein the plurality of cine loops of MRI images of cardiac wall motionare synchronized to one another and the at least one cine loop of MRIimages of cardiac perfusion.
 10. The workstation of claim 8, wherein atleast one of the plurality of cine loops of MRI images of cardiac wallmotion is registered to the at least one cine loop of MRI images ofcardiac perfusion.
 11. The workstation of claim 7, wherein the userinterface allows a user to select display with the user interface isconfigured to display the plurality of cine loops of MRI images ofcardiac wall motion and the at least one MRI image of cardiac perfusionin real-time or near real-time.
 12. The workstation of claim 7, whereinthe user input is configured to accept user input to rapidly adjust atleast one of contrast, brightness, gamma or another display level of abaseline cine loop image, and wherein the workstation and/or display isconfigured to automatically propagate the adjustment to the other cineloops without adjusting each one separately to thereby provide aclinician with patent information for safer administration of thecardiac stress test.